Which of the following is a contributing factor in caustic corrosion?

API RP 571 describes under Caustic Corrosion:

“One of the significant contributing factors is caustic accumulation in low-flow or stagnant areas, especially in heat-traced lines or around steam injection points.”

“Localized heating can concentrate caustic solutions, promoting corrosion even in carbon or stainless steels.”

Thus, option C (heat-traced equipment) is the correct and technically accurate choice.